Connection two cDAQ 9185 together and Synchronizing them

[ataalkhatib97]

Hello! 

Currently I'm working on upgrading a project, where I have Two cDAQ 9185 chassis that should work together, to fully automate the system.

Current condition is as below:

- One cDAQ 9185 4 slots chasse is installed and reading inputs using 4 NI-9219 Modules from 15 source (sensors/transducers..)

- The VI is using one DAQ assistance to collect all the readings at once and displaying it on the Front panel. 

- The sample frequency is set to 1 Hz (1 reading per second)

- The control of the system is being done Manually using hand operated valves.

I'm working on the below:

- I have to install and connect the second new cDAQ 9185 chasse to the system.

- This new cDAQ 9185 chasse will be responsible of "Generating output signals" to move/control the new electric expansion valves that I'm going to install.

- Those signals will be generated based on the readings I'm getting from the first cDAQ 9185 that is already installed using a PID controller VI.

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Currently, since there is only 1 PFI port on each chasse, is synchronizing the Timing signal alone enough to do the job ? or Timing and Trigger are required ?    If both are required, do I have to buy and install two of the NI 9469 C module ?

Should I connect both Chassis to the HOST Pc directly ? or I should connect a slave to the master, and the master only will be connected to the HOST PC ??

I'm very new to LabVIEW and NI products, and Controls in general. so please be patient with me.

Ata Alkhatib 

[ZYOng]

cDAQ-9185 are TSN-enabled chassis. You can daisy-chain them to form a synchronized system. See NI-DAQmx-Based TSN Synchronization Accuracy Explained

When it comes to controlling the device, you can use Time Trigger to start all tasks on multiple chassis at the same time. See Figure 1 of Time-based Synchronization of Analog Input C Series Modules with NI-DAQmx in LabVIEW

[ataalkhatib97]

Thank you ZYOng for your fast reply. It was too helpful!

Now the first part is answered and it is clear to me, thanks!

For the second part, As shown below

the one DAQ Assistant is used collect all the data

Now, I will be creating also a new one-DAQ assistant to output all the signals, how can I connect them (including all the modules and channels on both Chassis) in the below code:

[ZYOng · Accepted solution]

You can configure the Time Trigger under the Triggering tab.

However, I would not recommend using DAQ Assistant. It is buggy and has many limitations. For instance, you cannot set the Start Time for time trigger programmatically. I would suggest you explore the shipping examples. See Help >> Find Examples >> Hardware Input and Output >> DAQmx >> Analog Input >> Voltage - Continuous Acquisition. This example includes time trigger as well.

To learn more about the DAQmx API, see Learn 10 Functions in NI-DAQmx and Handle 80 Percent of Your Data Acquisition Applications

[ataalkhatib97]

Thank you!